Wait time

• The time required for the device to produce a desired quantity of safe water that is acceptable to end users.

Key indicators

• Threshold: the time to treat the volume in the upper container should be overnight (~8 hours) or less.
• Users prefer faster flow rates but may tolerate extended times (6 to 8 hours) needed to treat the total volume of water in a device.

Notes and exceptions

• Turbidity and dissolved solids are key variables in source water and can determine the effectiveness and user satisfaction with HWTS products.
• Filter elements may be made modular allowing adaptation to local conditions.

Supporting evidence

• Rainwater Harvesting Technical Brief. Wateraid, unpublished data, 2010.
• World Health Organization (WHO). Guidelines for drinking-water quality: Incorporating 1st and 2nd addenda, Vol.1, Recommendations, 3rd ed. Geneva: WHO; 2008. Available at: http://www.who.int/water_sanitation_health/dwq/fulltext.pdf.
• PATH HWTS Tradeoff Matrix. HaloSource, unpublished data, 2009.
• Full list of supporting evidence and additional materials.